Study of the function of the inner ear in carts. The mechanical vibrations of the basilar membrane will be measured in response to sound applied to the ear. The measurements are to be made with an optical interferometer capable of measuring vibration amplitudes as low as 3 x 10 to the minus 12th power cm. The basic procedure consists of removing the round window membrane and dropping microscopic mirrors onto the basilar membrane at selected spots. A laser beam is reflected off one of these mirrors and interferometric measurements of the basilar membrane vibrations are made. The surgical manipulations necessary to gain access to the cochlea invariably produce trauma to the delicate organ. The state of the cochlea is therefore to be monitored during the experiment using (1) cochlear microphonic potentials and (2) gross neural potentials (N1) in response to tone pips. At the completion of the experiment, cochleas are fixed and examined histologically for damage. The generation of the signals and the analysis of the response is to be carried out using a Data General Eclipse Computer System.